Less us ponder the subject of having children in the face of the existence of aging coupled with the possibility of progressively defeating aging - perhaps to the point where some of us alive today will escape age-related death by the skin of our teeth. Or perhaps not if we don't get our act together here and now. Evidently we need to have children in order to have the chance of incrementally defeating aging by building ever better versions of a biological repair kit to reverse ever more of the damage that causes degeneration and death. This task is one of decades, long enough that it may be today's researchers who start the job, but it'll be younger hands that finish it - their children and grandchildren. Yet creating people is somewhat like drafting them into a war and a human condition that they didn't ask for:
There's a task we need you for, son, you and the rest of your generation. We may or may not manage to complete it, but we certainly won't without your help - and if we don't get this done, we're dead all too soon, a slow death, heavy on the pain and suffering. We'll be dragged away first so you get to see the end in all its horror, with plenty of sleepless nights to think it over before it happens to you as well. Oh yes, and most people don't see the need for any of this work and think the pain and suffering and death is just dandy. So that's the deal, a raw one all round - welcome to the asylum, son. No need to thank me.
I'm sympathetic to the hedonistic imperative view of pain and priorities in technological development, and I also think there's a fair but short-sighted argument to be made for nihilism along the lines of voluntary species extinction. It runs something along the lines of a utilitarian consideration of suffering, slavery, existence, natural rights, and similar concerns.
I call that short-sighted because, if we're going to be utilitarian, we should consider that the point and beneficiary of all this technological development - not to mention the bone mountain of suffering and corpses we stand upon and continue to build - is very much not us. Our own longevity and diminished future suffering is a tiny side-effect on the way to providing massively greater benefits to our future descendants, be they biological or machine intelligences. They will be so greatly endowed by the cumulative efforts in advancing technology that ensuring their existence (and ensuring that it comes about as soon as possible) will far and away outweigh our needs in any utilitarian consideration. We are short-lived, small in number, small in mind, and planet-bound evolved intelligences, while our descendants of future centuries will not be any of those things. There will be trillions of them, a near infinite variety of forms of mind, ageless, absent suffering, and hopefully wiser than us for it. They will exist because we, our forebears, and our children suffered the limitations and risks of our present existence in order to build the road that little bit further - and because we chose to inflict the same on others by bringing them into being.
So having children still looks to me largely like throwing new people into a horrible situation in order that some of them will try make it better - and with some hope that they might benefit as individuals, but also the great risk that they will not, and suffer greatly as a consequence. Beyond that, there is an abstract grail that will be enjoyed by people yet to come - our descendants made in biology or machinery - who we will likely never know, and whose era will be brilliant and golden beyond our imagining, but only if we strive to lay the foundation stones here and now.